DigestInputStream JDK 1.6)

Methods

public int available () throws IOException [Inherited From FilterInputStream]

Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream.

public void close () throws IOException [Inherited From FilterInputStream]

Closes this input stream and releases any system resources associated with the stream.

Closes this input stream and releases any system resources
associated with the stream.
This
method simply performs in.close().
Throws:
- IOException - if an I/O error occurs.
See Also: FilterInputStream.in,

public MessageDigest getMessageDigest ()

Returns the message digest associated with this stream.

publicsynchronized void mark (int readlimit) [Inherited From FilterInputStream]

Marks the current position in this input stream.

Marks the current position in this input stream. A subsequent call to the reset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes.

The readlimit argument tells this input stream to allow that many bytes to be read before the mark position gets invalidated.

This method simply performs in.mark(readlimit).
Parameters:
- readlimit - the maximum limit of bytes that can be read before the mark position becomes invalid.
See Also: FilterInputStream.in, FilterInputStream.reset(),

public boolean markSupported () [Inherited From FilterInputStream]

Tests if this input stream supports the mark and reset methods.

Tests if this input stream supports the mark
and reset methods.
This method
simply performs in.markSupported().
Returns: true if this stream type supports the mark and reset method; false otherwise.
See Also: FilterInputStream.in, InputStream.mark(int), InputStream.reset(),

public void on (boolean on)

Turns the digest function on or off.

Turns the digest function on or off. The default is on. When
it is on, a call to one of the read methods results in an
update on the message digest. But when it is off, the message
digest is not updated.
Parameters:
- on - true to turn the digest function on, false to turn it off.

public int read () throws IOException [Overrides FilterInputStream] [Specified in InputStream]

Reads a byte, and updates the message digest (if the digest function is on).

Reads a byte, and updates the message digest (if the digest
function is on). That is, this method reads a byte from the
input stream, blocking until the byte is actually read. If the
digest function is on (see on), this method
will then call update on the message digest associated
with this stream, passing it the byte read.
Returns: the byte read.
Throws:
- IOException - if an I/O error occurs.
See Also: MessageDigest.update(byte),

public int read (byte[] b) throws IOException [Inherited From FilterInputStream]

Reads up to byte.length bytes of data from this input stream into an array of bytes.

Reads up to byte.length bytes of data from this input stream into an array of bytes. This method blocks until some input is available.

This method simply performs the call read(b, 0, b.length) and returns the result. It is important that it does not do in.read(b) instead; certain subclasses of FilterInputStream depend on the implementation strategy actually used.
Returns: the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.
Parameters:
- b - the buffer into which the data is read.
Throws:
- IOException - if an I/O error occurs.
See Also: FilterInputStream.read(byte[], int, int),

public int read (byte[] b, int off, int len) throws IOException [Overrides FilterInputStream]

Reads into a byte array, and updates the message digest (if the digest function is on).

Reads into a byte array, and updates the message digest (if the
digest function is on). That is, this method reads up to
len bytes from the input stream into the array
b, starting at offset off. This method
blocks until the data is actually
read. If the digest function is on (see
on), this method will then call update
on the message digest associated with this stream, passing it
the data.
Returns: the actual number of bytes read. This is less than len if the end of the stream is reached prior to reading len bytes. -1 is returned if no bytes were read because the end of the stream had already been reached when the call was made.
Parameters:
- b - the array into which the data is read.
- off - the starting offset into b of where the data should be placed.
- len - the maximum number of bytes to be read from the input stream into b, starting at offset off.
Throws:
- IOException - if an I/O error occurs.
See Also: MessageDigest.update(byte[], int, int),

publicsynchronized void reset () throws IOException [Inherited From FilterInputStream]

Repositions this stream to the position at the time the mark method was last called on this input stream.

This method simply performs in.reset().

Stream marks are intended to be used in situations where you need to read ahead a little to see what's in the stream. Often this is most easily done by invoking some general parser. If the stream is of the type handled by the parse, it just chugs along happily. If the stream is not of that type, the parser should toss an exception when it fails. If this happens within readlimit bytes, it allows the outer code to reset the stream and try another parser.
Throws:
- IOException - if the stream has not been marked or if the mark has been invalidated.
See Also: FilterInputStream.in, FilterInputStream.mark(int),

public void setMessageDigest (MessageDigest digest)

Associates the specified message digest with this stream.

public long skip (long n) throws IOException [Inherited From FilterInputStream]

Skips over and discards n bytes of data from this input stream.

Skips over and discards n bytes of data from this input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. This may result from any of a number of conditions; reaching end of file before n bytes have been skipped is only one possibility. The actual number of bytes skipped is returned. If n is negative, no bytes are skipped.

The skip method of this class creates a byte array and then repeatedly reads into it until n bytes have been read or the end of the stream has been reached. Subclasses are encouraged to provide a more efficient implementation of this method. For instance, the implementation may depend on the ability to seek.

This method simply performs in.skip(n).

public String toString ()

Prints a string representation of this digest input stream and its associated message digest object.